Passive seat belt system

ABSTRACT

A passive seat belt system having a seat belt for restraining a wearer in the seat from being thrown away when large acceleration or deceleration has been exerted on the wearer, a reinforcing strip combined with the seat belt to give the seat belt a rigidity so that the seat belt can stretch by the help of only the above reinforcing strip, and a driving unit connected with the reinforcing strip for driving the strip so that the seat belt can automatically be stretched forward over the seat, whereby the wearer gets in and out of a vehicle very freely.

RELATED APPLICATION

This application is a division of our copending parent application Ser.No. 595,319, filed July 11, 1975 now U.S. Pat. No. 4,004,829.

BACKGROUND OF THE INVENTION

This invention relates to a passive seat belt system for vehicles whichautomatically fastens and unfastens the seat belt in accordance withwearer's intentional movement of getting in and out.

Conventionally, the seat belt is fastened and unfastened manuallly.However, because of the troublesomeness, such as seat belt system hasnot been always used, resulting in poor protection of unbeltedoccupants. To cope therewith, it has been proposed to fasten andunfasten the seat belt automatically. However, such a system alsoprovides an obstacle for the free entry and exit of the occupants,because of its many complex parts, such as rails, hangers, limitswitches and so on, which result in high cost and poor reliability.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a simple passive seatbelt system which can achieve sufficient automatic fastening andunfastening of the seat belt at low cost and with high reliability.

Another object of the present invention is to provide a passive seatbelt system having a convex spring on a ordinary seat belt so as to givethe seat belt a rigidity so that it functions as a complete passive seatbelt with simple construction and low cost. Another object of thepresent invention is to provide a passive seat belt system having astrip of spring which is inserted into a tubular seat belt so as to givethe seat belt a rigidity, thereby fastening and unfastening the seatbelt automatically.

Another object of the present invention is to provide a passive seatbelt system having two strips of spring, each of which has differentlength with each other, inserted also into a tubular seat belt so as togive the seat belt rigidity, thereby obtaining automatic fastening andunfastening operations with low cost and high reliability.

Other objects, features and advantages of the present invention willbecome apparent from the following detailed description of the preferredembodiment.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a schematic view of an embodiment of passive seat belt systemof the present invention in closed-door condition.

FIG. 2 is a schematic view of the embodiment shown in FIG. 1 inopen-door condition.

FIG. 3 is a cross-sectional view of the seat belt of the passive seatbelt system.

FIGS. 4 and 5 show schematic views of the driving unit of the passiveseat belt system.

FIG. 6 shows an electric circuit for the driving unit shown in FIG. 4and 5.

FIGS. 7 and 8 show schematic views of the other embodimentsrespectively.

FIG. 9 shows a plan view of the other embodiment of the passive seatbelt system in closed-door condition.

FIG. 10 shows a schematic view of the principle mechanism of the passiveseat belt system shown in FIG. 9.

FIG. 11 shows a cross-sectional view taken along the line A--A in FIG.10.

FIG. 12 shows a schematic view of the embodiment shown in FIG. 9 inopen-door condition.

FIG. 13 shows another embodiment of the passive seat belt system inclosed-door condition.

FIG. 14 shows another embodiment of the passive seat belt system inclosed-door condition.

FIG. 15 shows the other embodiment of the driving unit of the passiveseat belt system.

FIG. 16 shows an electric circuit for the above embodiment.

FIG. 17 shows a schematic view of the other embodiment of the passiveseat belt system.

FIG. 18 shows a partial cross-sectional view of the embodiment shown inFIG. 17 taken along the line B--B.

FIG. 19 shows schematic view of the ends of the strips shown in FIG. 17.

FIG. 20 shows a cross-sectional view of the seat belt in FIG. 17 takenalong the line C--C.

FIG. 21 shows a plan view of the above embodiment in open-doorcondition.

FIG. 22 shows a plan view of the above embodiment in closed-doorcondition.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Referring first to FIGS. 1 and 2, one end of the seat belt 1 is fastenedto a rear and lower position of the door 2 through an anchor 3, whilethe other end is fastened to a retractor 4 fixed on the center of thefloor of the vehicle. On one side of the seat belt 1 near the door 2 isfixed a strip of convex metal sheet 5 which has an arched cross-sectionand develops a rigidity against a bending force in a direction from itsend to the swelling center, while having little rigidity against abending force in the reverse direction. On one side of the seat belt 1near the retractor 4 is fixed another convex metal sheet strip 5' thesame as the strip 5 above. The convex metal sheet 5 or 5' is of the typesuch as well-known convex strips which are easily pulled out in astraight line. As in FIG. 3, the convex metal sheet is stitched orbonded to the seat belt. The length of the sheets 5 and 5' is chosen notto contact with or bother the occupants in the closed-door condition. Adriving unit 6 pulls out the seat belt 1 by the convex metal sheet inaccordance with closing or opening of the door 2 and with the pulled outlength of the seat belt 1. When the door 2 is closed as in FIG. 1, theretractor 4 retracts the seat belt 1 so that the seat belt can restrainthe occupants. The seat belt 1 is pulled out by the driving unit 6straight from the retractor 4 toward the front portion of the cabinbecause of the rigidity of the convex metal sheet 5' fixed on the seatbelt 1, while the seat belt 1 near the door 2 elongates straight alongthe surface of the door 2 because of the rigidity of the convex metalsheet 5, thereby to set the seat belt 1 automatically in a suitablemanner not to interrupt the occupant's free entry and exit.

Referring next to FIGS. 4, 5 and 6, a motor 7 operates as a power sourceof the driving unit 6, wherein there is provided a worm gear 8 at an endof a shaft of the motor 7. The worm gear 8 engages with grooves 5aformed on the convex metal sheet 5' to enable the motor 8 to pull outthe seat belt 1 from the retractor 4. The retractor 4 consists of a body9 fixed on the vehicle body, a reel 10 rotatable with respect to thebody 9 and connected with the end of the seat belt 1, a retractingspring 11 exerting retracting force to the reel 10 and a lockingmechanism (not shown) for locking the seat belt when acceleration ordeceleration above a preset level is developed on the vehicle.

The motor 7 is fixed rotatably on an aperture 7a formed in a housing 7bas shown in FIG. 5. A solenoid 12 is energized when the door 2 is openedto draw an armature 12a. To the housing 7b of the motor 7 are fixed oneends of springs 13 and 14, while the other ends of which are connectedto the armature 12a and vehicle body respectively. When the door isclosed, the worm gear 8 is detached from the convex metal sheet 5',since the motor 7 and worm gear 8 are then positioned as shown by abroken line in FIG. 5. As the seat belt is pulled out, the worm gear 8,and the motor, are gradually shifted to the right. Numeral 15 is anormally closed limit switch which opens and closes in accordance withthe position of the motor 7, i.e., when the pulled out length of seatbelt 1 reaches a preset value to have a preset clearance between themotor 7 and itself, the limit switch 15 opens. As shown in FIG. 6, thelimit switch 15 is connected to the motor 7 and battery 17 so as toenergize the motor 7 in response to its closure. A door switch 16 isconnected to the battery 17 to energize both motor 7 and solenoid 12 inresponse to its closure.

The operation of the above constructed embodiment will be explainedbelow. When the door 2 is in closed condition, the door switch 16 is inan open state to deenergize the solenoid 12; therefore the motor 7 ispositioned at a location shown in broken line in FIG. 5 by the action ofthe spring 14. Consequently the worm gear 8 does not engage with thegrooves 5a of the convex metal sheet 5', therefore the retractor 4 fullyretracts the seat belt 1 by the retracting spring 11 as shown in FIG. 1.However, if the occupant is in the seat, the seat belt 1 is not fullyretracted, a portion sufficient for securing the occupant remaining. Onthe other hand, when the door 2 is opened, the door switch 16 is closedso that the solenoid 12 is energized, therefore the armature 12a drawsthe motor 7 through the spring 13 until the worm gear 8 engages with thegrooves 5a. Since the limit switch 15 is of normally closed type, themotor 7 begins rotation, upon opening the door 2, therefore the seatbelt 1 is pulled out in the direction of an arrow X in FIG. 5. The seatbelt 1 is thus pulled out to extend straight because of the rigidity ofthe convex metal sheet 5' fixed on the seat belt 1. On the other hand,the seat belt 1 coming from the anchor 3 also becomes straight over thesurface of the door 2 because of the rigidity of the convex metal sheet5. When the seat belt 1 is continuously pulled out from the retractor 4,the motor 7 gradually moves toward the limit switch 15 and when thelength of the pulled out seat belt 1 reaches the definate value, themotor 7 pushes the limit switch 15 so as to open it, therefore the motor7 is deenergized to terminate the pulling out of the seat belt 1.However, since the solenoid 12 is still energized so as to draw thearmature 12a, holding the engagement of the worm gear 8 and grooves 5a,the seat belt 1 is not pulled in by the retracting spring 11 of theretractor 4 so that the seat belt 1 is held in the position of FIG. 2.Therefore the occupant can easily get in and out of the vehicle withoutbeing obstructed by the seat belt. When the door 2 is closed after theoccupant gets into or out of the vehicle, the door switch 16 is openedimmediately so as to deenergize the solenoid 12, therefore the motor 7returns to the position shown in broken line in FIG. 5 by the force ofspring 14. In this moment, as the worm gear 8 separates from the convexmetal sheet 5', the seat belt 1 is pulled into the retractor 4 by theretracting spring 11 to return to a position as shown in FIG. 1. Apinion gear 18 fixed on one end of the shaft 7 as shown in FIG. 7 can besubstituted for the above worm gear 8. In that case, a different shapeof groove 5b should be provided on the convex metal sheet 5' to engagewith the pinion gear 18 as shown in the same drawing. A friction roller19 shown in FIG. 8 can also be substituted for the worm gear 8 to pullout the seat belt 1 by the friction engagement. In this case, the convexmetal sheet 5' is possibly built in the seat belt 1, which gives betterappearance. Instead of the convex metal sheet 5 and 5', synthetic resinconvex sheet is available for that purpose. Further, the above mechanismis also applicable to other seat belt systems consisting of two seatbelts for chest and waist of the occupants.

Referring to FIGS. 9, 10, 11 and 12, one end of the seat belt 1 isconnected to the retractor 4 fixed on the floor (not shown) of thevehicle, while the other end is connected with the door 2 through theanchor 3, wherein the retractor 4 is of a known type which has a springfor always exerting a pull in a retracting direction and has a lockingmechanism for locking the seat belt when an acceleration above apredetermined value is exerted on the vehicle. The seat belt 1 has alongitudinary extending thin space 1a therein into which a thin metalstrip 5 which bears a rigidity in only one direction is inserted throughan aperture 1b formed also in the seat belt 1. The thin metal strip 5 isof the type such as a spring for clock, convex measure and the like,which have a rigidity in one direction and elasticity in the otherdirection. One end of the strip 5 is connected with a reel 27 rotatablymounted on a retainer 26 fixed on the vehicle body. The strip 5 isinserted into the inner thin space 1 a at one end, while most part of itis wound around the reel 27 at free condition. A stopper 28 prevents thewound strip from loosening. To the reel 27 is also connected one end ofa wire 29 the other end of which is connected with a fixed point 31through a roller 30 fixed on the door 2 without loosening. The reel 27and wire 29 work as a driving unit. When the door 2 is closed as shownin FIG. 9, there does not arise a tension on the wire 29 so that theseat belt 1 is in a fully wound position or occupant restrainingposition, although the strip 5 is in a state inserting a part thereofinto the inner thin space 1a. Then, when the door 2 is opened as shownin FIG. 12, the distance between the roller 30 and fixed point 31increases, thereby exerting a pull on the wire 29 in a direction Y sothat the reel 27 is energized to draw out the strip 5. In accordancewith the rotation of the reel 27, the strip 5 is deeply inserted intothe inner thin space 1a and then the strip 5 extends straight along thesurface of the door 2 because of the rigidity of itself as shown in FIG.12. The seat belt 1 is pulled out to the front part of cabin so that theoccupant or wearer is not obstructed. When the door 2 has been closed asshown in FIG. 9, the distance between the roller 30 and fixing point 31decreases and the pull exerted on the wire 29 disappears, so that thestrip 5 is wound around the reel 27 by the winding force of itself todraw the strip 5 in the inner space 1a back to the reel 27. Therefore,the seat belt 1 loses rigidity to make it free, so that the seat belt 1is retracted into the retractor 4 to go back to the initial full woundstate or occupant restraining state. Then, the wire 29 goes back to theinitial state without loosening therebetween, as the reel 27 rewinds thewire 29.

Referring to FIG. 13, there is provided a pinion 40 which is rotatablyfixed on the door 2 and has a shaft 41 fixed to the pinion 40 itself.One end of the wire 29 is connected with the shaft 41. There is alsoprovided a curved rack 42 which has a center identical with that of thedoor 2 so that it can engage with the pinion 40. The thin metal strip 5is the same member as used in the above embodiment, i.e., it is woundaround the reel (not shown) by the self-winding force thereof when thedoor 2 is closed. When the door 2 is opened, the pinion 40 which engageswith the rack 42 rotates in response to the turning of the rack 42 in adirection shown Z, therefore the shaft 41 retracts the wire 29 to rotatethe reel so that the strip 5 may be pulled out in a direction shown W.

In FIG. 14, the strip 5 is of the type which holds a straight pulled outfigure as its free state when the door 2 is in open condition. Thereforewhen the door is closed, the pinion 40 engaged with the rack 42 rotatesin a direction shown by V, so that the shaft 41 retracts the wire 29 torotate the reel retracting the strip 5 in a direction shown by U. Inthis embodiment, the strip 5 extends deeply in the inner space 1a of theseat belt 1 by the self-elongating force so that the seat belt 1 ispositioned at the front of the cabin when the door 2 is opened to takeoff the tension on the wire 29. Therefore the occupant can freely getinto or out of the vehicle.

Referring to FIGS. 15 and 16, the strip 5 is of the type which coilsaround the reel 27 in its free state. The reel 27 is of the type whichis rotated by a motor 43 capable of reverse rotation and speedreduction. The motor 43 is controlled by a limit switch 44 which openswhen the strip 5 is pulled out over a preset length, the other limitswitch 45 which opens when the wound volume has reached a preset valueand the door switch 46 which operates according to the movement of thedoor 2.

When the door 2 is in the closed condition, the door switch 46 isconnected with a closed terminal 46b, however the motor 43 is notenergized if the wound volume of the strip 5 is over a definite value toopen the limit switch 45. When the door 2 is in the open condition, themotor 43 is energized through the limit switch 44 if the door switch 46is connected with an open terminal 46a. Consequently the strip 5 iswound out from the reel 27 to be inserted into the inner space 1a of theseat belt 1 and to close the limit switch 45. When seat belt 1 isextended to the front of the seat so as to elongate the strip 5 over thepreset length, the limit switch 44 opens to stop the rotation of themotor 43. When the door 2 is closed after the occupant has gotten in andout, the door switch 46 is connected with the closed terminal 46b sothat the motor 43 is energized through the limit switch 45 to rotate inthe reverse direction, therefore the strip 5 is wound around the reel 27and the seat belt 1 is also retracted by the retractor (not shown).Although the motor 43 is adopted in this embodiment, it is just anexample of the driving mechanism for the strip 5 so that the generaloperation thereof is as same as that in the above embodiments as awhole. Further as the force of the door 2 is utilized in thisembodiment, the driving mechanism for the strip 4 is very simple andinexpensive.

Referring next to FIGS. 17 and 18, there are provided thin strips 55aand 55b which are of the type such as clock coil and convex measurehaving a elasticity in one direction and a rigidity in the otherdirection. The strips 55a and 55b are wound around the reels 56 and 57respectively by the self-winding force thereof. The reel 56 is rotatablysupported on a retainer 62 fixed on the door 2 and has an axle 59connected with a shaft 60 of a motor 61 which has a speed reductionmechanism and fixed on the retainer 62. The reel 57 is rotatablysupported on a support member 63 which is attached on the door 2pivotaly around an aperture 64. There is also provided a spring 65,which pulls the support member 63 toward the retainer 62 thereby tobring the reel 56 into contact with the reel 57 so that the drivingforce of the motor 61 can be transferred to the reel 57 through afriction engagement of the respective periphery of the reels. Thediameter of the reel 56 is made a little larger than that of the reel 57so that the winding speed of the strip 55b may become a little largerthan that of the strip 55a. Arms 67 rotatably supported by supportingpins 68 have rollers 66 at one ends while the other ends 69 of which arefixed on the supporting member or retainer so that the rollers 66 pushthe wound strips 55a and 55b to prevent them from loosening. The strips55a and 55b are fixed to each other at their one ends by rivets 70 asshown in FIG. 19. At the ends of the strips 55a and 55b there isprovided a chip 71 for a smooth insertion of the strips into the innerspace 1a. The connected end of the strips is always inserted into thespace 1a of the seat belt 1. The motor 61 is capable of reverserotation. The motor 61 rotates the reel 56 in a direction shown T whenthe door 2 is opened and rotates the same in the reverse direction whenthe door 2 is closed, and is controlled to stop the rotation when thelength of the wound out strips 55a and 55b or the wound volume on thereels has reached a predetermined value. In FIGS. 21 and 22 showingrespectively a state of the seat belt 1 on open-door condition andclosed-door condition, the operation of the above embodiment will beexplained below. When the door 2 is in closed condition (FIG. 22), themotor 61 does not rotate, so that almost all of the strips 55a and 55bis wound on the reels 56 and 57. Then the seat belt 1 is in a conditionshown in FIG. 22, i.e., it is retracted fully by the retractor 4 or in acondition in which the occupant is fairly restrained thereby. On theother hand, when the door 2 is opened, the motor 61 starts rotation torotate the reel 56 in the direction T in FIG. 17 so that the strip 55ais pulled out from the reel 56. Then on account of the frictionengagement of the reels 56 and 57, the strip 55b is also pulled out fromthe reel 57, therefore both strips 55a and 55b are gradually insertedinto the inner space 1a of the seat belt 1 because of the rigidity ofthemselves. Since the diameter of the reel 56 is larger than that of thereel 57, the extending speed of the strip 55a is smaller than that ofthe strip 55b. Consequently the strip 55b is pulled out more than thestrip 55a, so that they are pulled out with a slight bend toward thereel 56, therefore they proceed in the inner space 1a so as to push theseat belt 1 toward the door 2, overcoming the retracting force of theretractor 4. When the strips 55a and 55b are pulled out over a presetlength, the rotation of the motor 61 is stopped, and then, since thestrips have pulled out the seat belt 1 enough to provide a space for theoccupant, the position of the seat belt 1 becomes suitable for theoccupant to get in and out of the vehicle. When the door 2 is closedafter the occupant has gotten on and off the vehicle, the motor rotatesin the reverse direction to rotate the reel 56 in the reverse directionof T, so that the strips 55a and 55b are retracted by the reels 56 and57, thereby retracting the seat belt 1 into the retractor 4. When theretracting volume reaches the predetermined value, the motor 61 stopsthe rotation to return the system to the initial state shown in FIG. 22.Thereafter the above described motion is repeated in response to theopening and closure of the door 2. In this embodiment, the strips areeasily wound on the reels in less power. Because, in case of two strips,the section modulus of each strip becomes one fourth of that of a singlestrip which is twice as thick as each of the two strips. Therefore theapproximate total power for winding the two strips becomes about a halfof that for the single strip, while the approximate total power for eachof the two strips becomes one fourth of that for the single strip. Thenumber of the strip is not restricted to the above embodiment. Thisfriction engagement type reels can also be driven by the force which isproduced when the door is opened. And the system is of course applicableto a shoulder belt and the like.

What we claim is:
 1. A passive seat belt system for a motor vehiclecomprising:a belt coupled at its one end to a vehicle door and havinginner thin space therein extending from said one end to the other end; aseat belt retractor secured to a floor of a motor vehicle and having aretracting reel rotatably received therein for windingly retaining saidbelt and a coil spring coupled to said retracting reel for normallybiasing said reel in a belt retracting direction; belt reinforcing meansof flat strip type inserted at its one end into said inner thin space ofsaid belt through an opening provided thereon; reel means rotatablymounted in said vehicle door for windingly retaining said beltreinforcing means; and driving means mounted in said vehicle door andcoupled to said reel means for extending said belt reinforcing meanswhen said vehicle door is opened, said belt reinforcing means extendingthrough said inner thin space in accordance with the extension thereofdriven by said driving means, and said driving means retracting saidbelt reinforcing means when said vehicle door is closed, and therebysaid belt reinforcing means is retracted from said inner thin space. 2.A passive seat belt system as set forth in claim 1, said beltreinforcing means is made of a thin metal strip having rigidity in onedirection and elasticity in the other direction.
 3. A passive seat beltsystem as set forth in claim 1, whereinsaid belt reinforcing means isnormally biased in a retracting direction by itself, and said drivingmeans includes: a shaft fixedly secured to said reel means; and a wireconnected at its one end to a vehicle body and wound at the other end onsaid shaft, whereby said wire drives said shaft together with said reelmeans in an extending direction when said vehicle door is opened, saidwire being restored to its initial condition by the retracting movementof said belt reinforcing means when said vehicle door is closed.
 4. Apassive seat belt system as set forth in claim 1, wherein said beltreinforcing means is biased in an extending direction by itself, andsaiddriving means includes: a shaft secured to said reel means; and a wireconnected at its one end to a vehicle body and wound at the other endthereof on said shaft, whereby said wire is extended from shaft whensaid vehicle door is opened to thereby enable said belt reinforcingmeans to extend by itself, and said wire drives said shaft together withsaid reel means in a retracting direction when said vehicle door isclosed to thereby retract said belt reinforcing means and to restoresaid wire to its initial condition.
 5. A passive seat belt system as setforth in claim 1, wherein said driving means includes:an electric motorhaving a rotary shaft coupled to said reel means; and switch means fordriving said electric motor in an extending direction when said vehicledoor is opened to thereby extend said belt reinforcing means, and fordriving said electric motor in a retracting direction when said vehicledoor is closed to thereby retract said belt reinforcing means.
 6. Apassive seat belt system as set forth in claim 1, whereinsaid beltreinforcing means includes a first and a second metal strips coupledtogether at their respective one ends, said reel means includes a firstand a second reel for respectively windingly retaining the other ends ofsaid first and second metal strip, said first reel being coupled to saidsecond reel for driving the same at a speed higher than that of saidfirst reel, and said driving means includes: an electric motor having arotary shaft coupled to said first reel; and switch means for drivingsaid electric motor in an extending direction of said belt reinforcingmeans when said vehicle door is opened and for driving said electricmotor in a retracting direction of said belt reinforcing means when saidvehicle door is closed.